1. Field of the Invention
This invention relates generally to packaging machinery and more specifically to an improved folder assembly for introducing a 180.degree. (single fold) or a 360.degree. (double fold) to the open top of a bag as the bag is transported through the packaging machine during a sealing operation.
2. Discussion of the Prior Art
In packaging machines used to seal paper bags containing a solid product, the open end of the bag is generally gripped between parallel flights of two endless chains and carried through a top trimmer station and either one or two creasing and folding stations where the previously opened end of the bag is folded over either once or twice to close and seal the bag. It is also a common practice to provide a suitable adhesive on the folded portion of the bag so that it will remain closed and sealed following discharge from the packaging machine.
In prior art bag sealing machines, the folder used to wrap or fold the end of the bag closed is generally a sheet metal member which is formed in a bending process to provide a predetermined profile in the path of the bag as it is carried along through the packaging machine. The profile is such that the open end of the bag is bent first at a 90.degree. angle, then to a 180.degree. angle, at which point a hot melt adhesive may be applied to the exposed folded surface of the bag. The bag may then be transported through a second similar formed sheet metal folding station where the end of the bag is further folded to a 270.degree. degree point and then to a 360.degree. point, resulting in a double wrapped closure.
The formed sheet metal folders of the prior art have suffered from two principal drawbacks. First of all, because of irregularities in the thickness of the material forming the open end of the bag to be closed, and because of the fact that there is substantially no give to the sheet metal folder, the bags tended to become jammed in the folding stations required that the machine be shut down while the jam is cleared. Again, because of the nature of the sheet metal folders employed, it proves quite difficult to clear the jam, often requiring the folding station to be disassembled from the machine so that adequate access may be had to remove the torn paper material jammed into the folder. Naturally, frequent jamming and long down-time to clear a jam seriously limits the through-put of the machine.
The present invention is deemed to be an improvement over the prior art in that it provides a folder assembly which is much less subject to jamming and which may readily be cleared if and when a jam should occur.